OpenWrt is described as a Linux distribution for embedded devices.
Instead of trying to create a single, static firmware, OpenWrt provides a fully writable filesystem with package management. This frees you from the application selection and configuration provided by the vendor and allows you to customize the device through the use of packages to suit any application. For developer, OpenWrt is the framework to build an application without having to build a complete firmware around it; for users this means the ability for full customization, to use the device in ways never envisioned.
Originally installed dd-wrt on my buffalo router, and suddenly want to try something different, so I flashed the latest version of openwrt (which FON based on) to my router and see if it works, as I heard that WBR-G54 works, mine is WBR-B11 which only with a different wireless chip.
After some time, the flashing is finished but seems the web interface is TOO SIMPLE for me, and the WAN port is incorrect, I need to manually edit the nvram myself by login to the router through SSH. It can go online afterwards, and I need to set iptables myself for port forwarding too.
Today I upgraded it to X-OpenWrt which is an extension to OpenWrt with a better looking and more powerful web interface, now I can use the web interface to set most of the things previously provided on dd-wrt.
Seems FON router firmware is based on OpenWrt... so let me try to flash my buffalo router into FON router tonight. Hope it is OK.